Followers of soccer, notably followers of the English national team, will be aware of tie importance of accurate shots at goal, for instance when the results of otherwise drawn games are decided by a `penal shoot out`. They will also be aware that a good penalty taker can make the difference between a side winning and losing.
Hitherto players have practised place-kicking primarily by shooting at either an open goal or one defended by a goalkeeper. The former is not a good simulation of a defended goal. The latter requires the presence of a goalkeeper and does not specifically train the footballer to shoot towards the optimal parts of the net.